A three-dimensional simulation of a parabolic trough solar collector system using molten salt as heat transfer fluid

• A coupled three-dimensional simulation is established.
• The performance of the PTCs with molten salt as HTF was obtained.
• The effects of key parameters on the PTCs with molten salt were achieved.
• The coupling characteristics of thermal and fluid of the receiver were disclosed.

Investigations on the thermal physics mechanisms of the parabolic trough collector systems (PTCs) play a vital role in the utilization of solar energy. In this paper, a three-dimensional simulation based on Finite Element Method (FVM) is established to solve the complex problem coupling with radiation, heat conduction and convection in the PTCs. The performances of the PTCs using molten salt as the heat transfer fluid were numerically studied, and the influences of the key operating parameters on the PTCs were investigated. As a result, it can be found that the circumferential temperature difference (CTD) of the absorber increases with the rising of the direct normal irradiance (DNI) and decreases with the increase of heat transfer fluid (HTF) inlet temperature and inlet velocity. With the velocity of the molten salt in the range of 1 m/s–4 m/s, the DNIs of 500 W/m2–1250 W/m2 and the inlet temperature of 623 K–825 K, the CTD of the absorber can reach 12 K–42 K. Furthermore, the numerical results indicate the non-uniform distribution of the solar energy flux affects the CTD of receiver while has a little influence on the thermal efficiency. The promising results will provide a reference for the design of the novel parabolic trough solar collectors.